Portable Arc Welder

ABSTRACT

In embodiments, a welding apparatus includes an automated wire feed mechanism to output wire at a wire feed rate, where the wire is to provide a welding arc to a weld site. The wire feed rate is based at least in part on selected power to be provided to the weld site. Additional embodiments are described and claimed.

This application claims priority to U.S. patent application Ser. No.14/806,897 filed Jul. 23, 2015, and to U.S. Provisional PatentApplication Ser. No. 62/027,924, filed Jul. 23, 2014, and the contentsof both of these Applications are hereby incorporated by reference.

TECHNICAL FIELD

Embodiments pertain to portable arc welding.

BACKGROUND

Welding enables joining of two or more objects, creating a joint that istypically stronger than, e.g., low temperature soldered joints. One formof welding is arc welding, accomplished by applying an electric arc tosurfaces of objects to be joined, melting base material, and feedingfiller material to create a molten pool , e.g., by feed of a weld wirethat melts and forms a “puddle” to form a weld that joins the objects.

Arc welding typically requires a high power (e.g., large electriccurrent). Typically arc welding is accomplished via use of a stationaryarc welder that receives power from a stationary source such as from apower grid, as alternating current (AC). Arc welding typically occurs ata location that can receive power from the power grid. In remotelocations, if arc welding is to be performed, use of an electricgenerator may be needed to supply ample power for an arc welder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an apparatus, according to an embodiment.

FIG. 2 is a block diagram of a system, according to another embodiment.

FIG. 3 is a block diagram of a system, according to another embodiment.

FIG. 4 is a flow diagram of a method, according to an embodiment.

FIG. 5 is a flow diagram of a method, according to another embodiment.

DETAILED DESCRIPTION

In embodiments, a welding apparatus provides a portable device withwhich to weld. In embodiments, the welding apparatus can be carriedwithin a back pack, or can be hand held, and permits welding to beconducted with relatively high power (e.g., up to 300 amperes of steadystate current). The welding apparatus can include a power source that iscapable of providing high power for welding, and can be adjusted toprovide power that can be selected for the welding application.Additionally safety features may be included to provide a “cold” weldingtip upon halting of welding. These and other features are describedwithin.

Embodiments may include one or more of the following features:

1) Low Contact Resistance Cell Interconnect/Battery Enclosure

Power to the welder may be supplied by high-power cells, such as LiFePO4pouch cells that are capable of delivering steady state currents thatmay range as high as 300 amperes (A). Pouch cells may have no structuralframe or enclosure, and can be constructed to be light in weight. Sincethe pouch cells have no rigid enclosure, a containment structure may beprovided in the welder. In embodiments, an arc welder integrates abattery containment structure as an integral part of a battery cellinterconnect system.

Reduction of circuit resistance may be employed in order to deliver highpower in order to perform a weld. Dissipative power may be expressed asa square of current times resistance (P=I²R). In order to provide forhigh currents (e.g., approximately 50 A to approximately 300 A)resistive elements of a welding circuit may be designed to have smallresistance. The cells are typically selected to have low internalresistance, to avoid overheating. Cell connections and cables may bedesigned for minimum resistance.

Embodiments of the battery enclosure provide a very low contactresistance interconnect system for the battery cells. Theinterconnect/enclosure system also functions to provide a flexiblethermal management (e.g., heat sink) for the cells and provides acompact and rugged protective enclosure for the cells.

2) Safety Shut-Down

In a high current battery application such as welding, it isadvantageous to maintain the battery power system within a safeoperating parameter range. In embodiments, the integrated power systemincludes a battery monitoring controller that monitors individual cellsor parallel cell modules within the battery, and may terminate thewelding process if any cell or module exceeds its predefined safeoperating limit. This safety shut-down feature is accomplished byturning off power to a weld wire feed motor within the welder, whichextinguishes the arc and load current. This safety shut-down featuremaintains the battery system within its safe operating parameter rangeavoiding possible damage to the equipment and injury to the operatorwhile also maximizing cycle life of the battery.

3) Weld Current Control

In embodiments the welding current is to be controlled by controlling afeed speed of a weld wire as it feeds into a molten weld puddle. Speedof the weld wire feed may be controlled through closed loop or open loopcontrol of the weld wire feed motor. A high rate of feed typicallyresults in a higher power consumption, and a low rate of feed typicallyresults in a lower power consumption.

4) Selectable Voltage Tap

To weld over a wide range of metal thicknesses and power levels it isadvantageous to have selectable or adjustable voltage. Embodimentsprovide selectable voltage through battery cell tap ports.

Use of tap ports in a multi-cell battery may present a difficulty incharging the battery, specifically in charging all cells to the sameFull Charge State (FCS). Embodiments include a battery charger that cancharge each cell to its full FCS without overcharging any cells, caseswhere a battery includes cells that have a wide difference in theirinitial charge state.

5) Retractable Weld Wire Cold Tip

A cold tip is a condition where a weld tip is disconnected from thepower source. With very high current circuits, instead of use of anelectro-mechanical “contactor” or relay, or expensive semiconductordevices, embodiments automatically retract the weld wire into anon-conductive wire tip (e.g., ceramic sleeve or other non-conductivesleeve) to isolate the tip from the weld wire. In embodiments, onreleasing the weld gun trigger, a controller automatically retracts theexposed length of weld wire into the non-conductive tip to isolate thetip from the wire and from the power source.

6) Weld Wire Speed Current Control

Embodiments control weld current by adjusting a speed at which the weldwire is fed into the molten metal weld pool. This speed control may bedone open or with closed loop feedback via a current sensor, e.g., ashunt or Hall type sensor.

7) A fully Integrated Handheld/Wearable Arc Welder.

Embodiments incorporate one or more of the above-described features toenable a wearable (e.g., enclosed within a back pack, shoulder bag, orholster) arc welder suitable for field use that is capable of providinga high current arc (e.g., approximately 50 A to 300 A) while beingportable, e.g., low weight (e.g., approximately 15 pounds or less; someembodiments weigh 6 pounds or less) and easily carried by a person dueto small occupied space of the arc weld apparatus (e.g., volume ofapproximately 450 cubic inches for a backpack welder, approximately 1200cubic inches for a “suitcase” welding system, and less than 150 cubicinches for an integrated portable handheld welder). Embodiments provideDC power to a weld wire feed control mechanism that is external to theenergy supply portion. Embodiments may include an energy supply andcontrol portion within a backpack or handheld case, which can enabletransport into and within remote locations. Other embodiments include ahand held arc welder (volume of approximately 150 cubic inches, andweight of approximately 5 to 7 pounds) that includes energy supply(e.g., battery), weld wire and tip, weld wire spool, wire feed mechanism(e.g., wire feed motor) and control electronics to provide a highcurrent arc (e.g., approximately 50 A to 300 A steady state), and mayoptionally include a safety mechanism to retract the weld wire into anon-conductive or sleeved tip when a trigger is released to result in acold tip that can prevent accidental arcing at the tip. Otherembodiments are also contemplated, and the above described embodimentsare non-limiting.

FIG. 1 is a block diagram of an apparatus, according to an embodiment.Apparatus 100 includes battery management logic 102, controller 104,battery 110, wire feed 112, weld wire 114, and current sensor 116.Optionally, apparatus 100 also includes one or more of charging logic118, inverter logic 120, and converter logic 122. The battery mayinclude one or more high power cells, e.g., light weight lithium cellssuch as pouch cells that are capable of delivering 20-300 amperes ofsteady state current for extended periods of time and that enable arcwelding to be performed. The controller 104 may be hardware such as amicrocontroller, a processor that includes at least one core, a systemon a chip (SOC), or other electronic circuitry, and may includefirmware, software, or a combination thereof.

In operation, a user may select a weld current at which to operate theapparatus 100, e.g., via a user input (e.g., any one of a plurality ofinput devices such as a potentiometer, keyboard, mouse, verbal input,etc.). The user input may also be received from, e.g., a start switchsuch as a trigger switch to initiate advancement of the wire by the wirefeed to establish the arc. In embodiments, a user pulls a trigger thatsends a signal to the controller 104 to initiate an arc. Current controllogic 106 within the controller 104 can initiate a start signal to theswitch 111 to engage the battery 110 to the wire feed 112, and also toprovide power to weld wire 114.

The wire feed 112 may be controlled by the controller 104, e.g., via thecurrent control logic 106, to feed weld wire 114 at a feed rate so as tomaintain a selected current level to the weld wire 114. The currentlevel may be determined by the user input received, e.g., as a selectionof weld power or weld current. The current control logic 106 maydetermine a rate of feed of the wire feed 112 to maintain anapproximately constant weld current, through use of a current sensor 116that can provide feedback for a feedback loop such as a closed loopfeedback mechanism. Alternatively, the wire feed speed may be setmanually by the user, e.g. with a potentiometer. A change in the weldcurrent may be detected via the current sensor 116, and may cause thecurrent control logic to adjust the rate of wire feed, e.g., by controlof a wire feed mechanism (e.g., motor speed of a wire feed mechanism(not shown)) in order to maintain a steady weld current through the weldwire 114. In some embodiments, the controller 104 controls the wire feed112 to create an intermittent arc, e.g., by stopping and starting thefeed rate, which may be useful in certain welding applications, e.g.,welding thin materials.

In embodiments, a trigger switch (not shown) is operated by the user.Squeezing the trigger switch can cause power to be sent to the wire feedmotor to advance the weld wire and establish an arc. Alternatively thetrigger can send a signal to the controller 104 to close a switch (notshown) that provides current to the wire feed 112 to operate the wirefeed motor and to deliver power to the weld wire 114. When the userreleases the trigger switch, the power to the wire feed motor isdisconnected, the wire stops feeding, and the arc extinguishes,terminating the welding current. In other embodiments releasing thetrigger can send a signal to control logic 106 causing the wire feed 112to stop feeding the wire, which extinguishes the arc and terminates flowof the welding current. Additionally, safety logic 108 within thecontroller 104 may generate a signal to cause the wire feed 112 toreverse the wire feed, e.g., retract a weld wire into an insulatingwelding tip isolating the tip from the powered wire. The weld wire tipmay be retracted into a tip or sleeve, e.g., a ceramic sleeve in thewelding tip (not shown), so as to prevent electrical contact of the wirewith the tip to avoid accidental arcing at the tip or wire. Release ofthe trigger switch may also cause the controller 104 to open the switch111 so as to remove power to the weld wire 114.

The battery management logic 102 may monitor a condition of each cell ofone or more cells within the battery 110. If the battery managementlogic 102 detects a critical cell condition, e.g., low cell voltage, orhigh temperature, the battery management logic 102 may terminate powerto the wire feed motor to stop the wire feed and terminate the weldingcurrent. Terminating the welding current quickly can prevent damage tothe battery due to low cell voltage or high temperature.

Optionally, the apparatus 100 may include charging logic 118 to rechargethe battery 110 from an external power source 124. The apparatus 100 mayoptionally include inverter logic 120 to enable alternating current (AC)126 to be output from the apparatus 100. The apparatus 100 mayoptionally include direct current (DC) to DC converter logic 122 toconvert a DC input 128 to a different DC voltage 130 to be madeavailable externally to the apparatus 100.

FIG. 2 is a block diagram of a system, according to an embodiment.System 200 includes an enclosure 201 that houses portions of a portablearc welder, and may house the portable arc welder in its entirety whenthe portable arc welder is not in use. The enclosure 201 includes abattery 202 that may include one or more cells, e.g., lithium cells suchas a lithium “pouch cell” (e.g., LiFePO4), each cell having a capabilityof delivering steady state DC current for use in arc weldingapplications. A selection of a number of cells may be based onanticipated welding applications. That is, the greater the powerrequirement, the larger the number of cells to be included in thebattery 202. The enclosure 201 of system 200 also includes circuitry 204(also “controller” herein) that includes has wire feed rate controllogic 206 and optionally includes safety logic 208. The enclosure 201also includes a parameter control panel/readout 210, and air vent 212that enables cooling during operation. A ground cable 214 couples theenclosure 201 to a ground clamp 216. A cable 218 couples the enclosure201 to a weld gun 220 that includes a weld wire spool motor (not shown),weld wire tip 222, weld wire 224, and weld activation trigger switch226.

In operation, the ground clamp 216 is attached to an electricallyconductive work piece object to be welded to provide an electrical pathfor an arc welding circuit that includes the object to be welded. A usermay select a power level (e.g., current level) via the parameter controlpanel 210. The user may squeeze the weld activation trigger switch 226that causes the controller 204 to couple the battery 202 to the weldwire 224 of the weld gun 220. When the weld wire 224 is broughtproximate to the object(s) to be welded, an arc is established(“struck”) at a weld site. The wire feed rate control logic 206 is tocontrol a rate of wire feed to the weld site based on feedback receivedvia a current detector 228. In embodiments, the wire feed rate to theweld site is to determine the current provided to the weld site. Forexample, a reduction in wire feed rate can result in a reduction in thecurrent to the weld site, and an increase in the wire feed rate canresult in an increase in current to the weld site. The wire feed ratecontrol logic 206 may be configured in an open loop or closed loopfeedback configuration to control the arc current.

In embodiments, the safety logic 208, when included in the system 200,can detect when the user releases the trigger 226 and responsive torelease of the trigger 226, the safety logic 208 can cause the wire feedmotor to reverse direction and withdraw the weld wire 224 from the weldsite. The weld wire can be withdrawn to within the tip 222 of the weldgun so that the weld wire is no longer exposed to potential accidentalarcing. e.g., contact with a grounded conductive object. The tip 222 maybe constructed from a non-conductive (e.g., a ceramic tip or tipsleeve), thus isolating the tip from the power source providingprotection against accidental arcing.

In embodiments, the enclosure 201 may occupy up to 1200 cubic inches (orless) of space, and may weigh 15 pounds or less, and is thereforeportable. In embodiments, the ground cable and ground clamp, and theweld cable and weld gun, may be storable within the enclosure 201, thusproviding a self-contained portable arc welder capable of delivering asmuch as 300 amperes of steady state direct current to a weld site.

FIG. 3 is a block diagram of a system, according to embodiments of thepresent invention. System 300 can serve as a hand held portable arcwelder and includes a wire spool 302, a wire feed mechanism 304 (e.g.,feed motor or other wire feed propulsion mechanism), a current sensor305, weld wire 306, a welding tip 307, an optional gas shield 308, atrigger switch 310, a handle 312, and a base 314 that includes battery316, battery monitor and control circuitry 318, a wire feed rate controllogic 320 and optionally includes safety logic 322.

In operation, a user may select a value of weld current or feed rate ofwire 306 to be delivered to a weld site (e.g. arc), via adjustment of aselection knob 317. The user may actuate the hand held weld system 300by squeezing the trigger switch 310, which causes the wire feed ratecontrol 320 to activate the wire feed mechanism 304 to deliver weld wirethrough the tip 307 to the arc at the selected rate. The wire feed ratecontrol logic 320 may control a wire feed rate of the wire 306 to thetip 307 from the wire spool 302 by adjustment of the feed mechanism 304.The wire feed rate control logic 320 may receive feedback from thecurrent sensor 305 (e.g., in a closed feedback loop) that providesinformation to determine whether to adjust the wire feed rate so as tomaintain a substantially steady weld current. Optionally, the gas shield308 may provide inert gas (e.g., helium, argon, etc.) to a weld site forinert gas welding.

When the user releases the trigger switch 310, the wire feed ratecontroller 320 stops the wire feed mechanism 304 from delivering wire sothat the arc is extinguished and the current stops flowing. Optionallythe safety logic 322 may cause the wire feed mechanism 304 to reversethe wire feed so as to retract the wire 306 into a non-conductivesleeved tip (e.g., a tip with a ceramic inner sleeve) so as to protectagainst accidental arcing of the tip 307 and possible burns to the userand to protect surrounding objects from a potential fire or other damagedue to uncontrolled arcing.

The hand held system 300 may be light in weight (e.g., 6 pounds orless), and may occupy a small space (e.g., 150-200 cubic inches), whichmay permit the hand held system 300 to be held and operated in one handof a user.

FIG. 4 is a flow diagram of a method, according to an embodiment. Atblock 402 of method 400, control circuitry receives an indication of aselected weld power (or weld current or weld wire feed rate). Continuingto block 404, the control circuitry (e.g., wire feed rate control logicincluded in or executed by the control circuitry) is to set a weld wirefeed rate based on the user selection. For example, when an arc isstruck between the weld wire and one or more objects to be welded, aninitial wire feed rate is set so as to produce an arc that consumes adesired weld power. The user may then adjust the selected current orwire feed rate to suit the weld application. Further adjustments may bemade as the welding continues.

Advancing to decision diamond 406, if an indication to supply power tothe weld wire is received (e.g., by the control circuitry, from a uservia a switch such as a trigger switch) proceeding to block 408 thecontrol circuitry causes power to be supplied to the weld wire feedmechanism to strike the arc. Additionally, the control circuitrygenerates a weld wire feed rate signal to be sent to the weld wire feedmechanism. The rate selected corresponds to the weld power, current, orfeed rate selected.

Advancing to decision diamond 410, if measured weld current is equal tothe selected weld current as measured by a current sensor, no change ismade to the weld wire feed rate. The control circuitry continues tomonitor the weld current at decision diamond 410. If the controlcircuitry detects a difference between the measured weld current and theselected weld current, proceeding to block 412 the control circuitryadjusts the weld wire feed rate (by adjusting a feed rate of a weld wirefeed mechanism) to reduce a difference between the measured weld currentand the selected weld current. Moving to decision diamond 414, if anindication to cease power to the weld wire is received by the controlcircuitry (e.g., user releases a trigger switch), advancing to block 416the control circuitry causes power to the weld wire to cease, e.g., bystopping the weld wire feed (removing power to the weld wire feedmechanism). By stopping the wire feed the arc is extinguished and thecurrent is terminated. If no indication to cease current to the weldwire is received, the method returns to decision diamond 410.

FIG. 5 is a flow diagram of a method, according to another embodiment.Method 500 begins at block 502, where control circuitry receives anindication to supply power to weld wire of an arc welder. Continuing toblock 504, the control circuitry couples a battery to the weld wire. Forexample, the control circuitry may receive an indication of a selectedweld current (or a selected wire feed speed) that may be selected by auser.

Advancing to block 506, the control circuitry monitors input for anindication of a shutdown (e.g., user releases a trigger switch, or a lowcell voltage indication is received by the control circuitry). If ashutdown indication is received, moving to block 508 safety logic of thecontrol circuitry (e.g., hardware, software executed by hardware,firmware, or a combination thereof) causes a weld wire feed mechanism toretract exposed weld wire so that a leading portion of the weld wire isretracted to within a non-conductive sleeve inside the weld tip. Theprotective tip serves as a “cold tip” and prevents a safety hazard ofaccidental arcing. That is, by retracting the electrically active weldwire, the tip is isolated from the active wire preventing accidentalarcing and possible subsequent damage to parts or equipment, injury orfire. The method ends at 510.

Embodiments may be implemented in code and may be stored on anon-transitory storage medium having stored thereon instructions whichcan be used to program a system to perform the instructions. Embodimentsalso may be implemented in data and may be stored on a non-transitorystorage medium, which if used by at least one machine, causes the atleast one machine to fabricate at least one integrated circuit toperform one or more operations. The storage medium may include, but isnot limited to, any type of disk including floppy disks, optical disks,solid state drives (SSDs), compact disk read-only memories (CD-ROMs),compact disk rewritables (CD-RWs), and magneto-optical disks,semiconductor devices such as read-only memories (ROMs), random accessmemories (RAMs) such as dynamic random access memories (DRAMs), staticrandom access memories (SRAMs), erasable programmable read-only memories(EPROMs), flash memories, electrically erasable programmable read-onlymemories (EEPROMs), magnetic or optical cards, or any other type ofmedia suitable for storing electronic instructions.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thescope of the present invention.

What is claimed is:
 1. A welding apparatus comprising: an automated wirefeed mechanism to output wire at a wire feed rate, wherein the wire isto provide a welding arc to a weld site and wherein the wire feed rateis based at least in part on selected power to be provided to the weldsite.
 2. The apparatus of claim 1, further comprising a wire feedcontroller that includes wire feed circuitry to control the wire feedrate.
 3. The apparatus of claim 2, further comprising a battery toprovide the selected power, wherein the wire feed controller, thebattery, and the automated wire feed mechanism are enclosed in aportable enclosure.
 4. The apparatus of claim 2, wherein the wire feedcontroller is to cause the welding arc to extinguish by removing powerto the automated wire feed mechanism responsive to an indication toextinguish the welding arc received from a user.
 5. The apparatus ofclaim 1, wherein the selected power is to be selected based on input tobe received from a user.
 6. The apparatus of claim 1, wherein the rateof the wire feed is to be controlled automatically based on closed loopfeedback to be received from a weld current sensor.
 7. The apparatus ofclaim 2, wherein the wire feed controller is to vary the wire feed rateover time to produce an intermittent welding arc.
 8. The apparatus ofclaim 2, wherein the wire feed controller is to reverse a direction ofthe wire feed mechanism so as to reverse a direction of output of thewire responsive to a stop command received from a user.
 9. The apparatusof claim 3, wherein the portable enclosure is less than or equal to 1200cubic inches in volume.
 10. The apparatus of claim 3, wherein theapparatus has an associated weight that is less than approximately 10pounds.
 11. The apparatus of claim 3, wherein the apparatus has anassociated weight that is less than or equal to approximately six poundsand the portable enclosure is less than or equal to 200 cubic inches involume.
 12. A welding system comprising: a wire feed mechanism to outputweld wire at a wire feed rate, wherein the weld wire is to enablewelding by conducting electrical current to a weld site; and controllercircuitry, wherein responsive to a stop indication to cease welding, thecontroller circuitry is to cause the wire feed mechanism to reverseoutput of the wire feed.
 13. The system of claim 12, further comprisinga welding tip to shield the weld wire from electrical contact with anexternal object after the reversal of the output of the wire feed thewire
 14. The system of claim 12, further comprising a battery thatincludes at least one cell and battery management logic to monitor acorresponding cell condition of each cell, wherein responsive to receiptfrom the battery management logic of an unsafe cell condition in one ofthe at least one cell, the controller circuitry is to cause the wirefeed mechanism to cease output of the weld wire to the weld site. 15.The system of claim 14, wherein the system includes an enclosure tohouse the wire feed mechanism, the controller circuitry, the batterymanagement logic and the battery, and wherein the enclosure has a sizethat is less than 200 cubic inches.
 16. The system of claim 15, whereinthe system has an associated weight that is less than or equal toapproximately 6 pounds.
 17. The system of claim 12, wherein thecontroller circuitry is to control the wire feed rate based at least inpart on the electrical current to be delivered by the wire, wherein theelectrical current is to be selected based on input received from auser.
 18. A method comprising: comparing, by controller circuitry, anelectric current that flows through a wire of a weld circuit, to aselected electric current value; and responsive to a difference betweenthe electric current and the selected electric current value, adjustinga feed rate of the wire to be fed to a weld site.
 19. The method ofclaim 17, further comprising responsive to an indication to open theweld circuit received by the controller circuitry, opening the weldcircuit by the controller circuitry by removing power to a wire feedmechanism to stop the feed of the wire to the weld site.
 20. The methodof claim 18, further comprising responsive to an indication received bythe control circuitry to open the weld circuit, reversing a direction offeed of the feed wire for a defined time period to cause the weldcircuit to open.